Ionization is a physical process of converting an atom or molecule of samples into an ion by adding or removing charged particles such as electrons or other ions. Depending on the level of impact energy, electrons may be ejected from atoms and molecules, or the molecules are fractured (i.e., fragmented) into a complement of fragments with diverse charge states. Ionization of gaseous molecules is conventionally initiated by photon bombardment, charged particle impact, ultraviolet radioactive ionization, or by thermal electron beams. Such conventional ionization techniques, however, utilize hard ionization and generate electrons and ions by means of radioactive elements, which are hazardous and not suitable for general applications. In modern low power high sensitive devices and/or detectors, a soft ionization technique is required to ionize the sample molecules at a pressure well above high vacuum regions.
In MEMS-based micro discharge device (MDD) detectors, soft ionization of gaseous samples is highly desirable. A typical MEMS-based detector can be utilized for detecting the presence of molecules in a gas sample on the basis of their optical emission spectrum as excited and emitted by that discharge. In majority of prior art MEMS-based detectors, the ionization sources are less efficient and the lifetime of prior art ionization sources is very short. Also, the ionizers utilized for low power high sensitivity devices are unable to provide soft ionization at pressures well above a high vacuum region. Additionally, MEMS-based detectors require additional power pumps to increase the pressure in the flow path, which utilizes more electrical energy. Therefore, the majority of prior art ionizers provides very low ionization efficiencies and also increases production costs.
Based on the foregoing, it is believed that a need exists for an improved micro discharge device (MDD) ionizer, which achieves soft ionization at high vacuum regions without the need for high power pumps.